1. Field of the Invention
The present invention relates to a camera in which mis-photographing is prevented from being caused by overlap of a finger.
2. Description of the Related Art
There is a camera provided with a lens barrel of a collapsible-mount type. In this type, the lens barrel is collapsed into a camera body at the time of non-usage, and is protruded toward the front of the camera body at the time of photographing. Such camera has a lens barrier for opening and closing a lens-barrel orifice so as to prevent dust or the like from entering the camera body through the lens-barrel orifice in a collapsible mount state.
As to a compact camera, a finger sometimes overlaps with a taking lens, a flash portion and so forth when the camera is held. Especially, with respect to a compact camera provided with a lens barrel of the collapsible-mount type and a lens barrier, there arises a problem in that a mechanism for opening and closing the lens barrier is sometimes damaged by holding the lens barrier with a finger when the lens barrier is moved. Moreover, there arises a problem in that a finger is sometimes interposed between the lens barrier and the lens-barrel orifice.
Further, a mechanism for driving the lens barrel is sometimes damaged by holding the lens barrel with a finger when the lens barrel is collapsed and protruded. In order to prevent the lens barrel from being damaged due to finger obstruction, cameras in which a driving mechanism for a lens barrel is protected are described in Japanese Patent publication Nos. 61-55099 and 7-27150, and Japanese Patent Laid-Open publication No. 7-218807. In such camera, when the lens barrel is abnormally stopped, electricity is discontinued to be supplied to a drive unit for the lens barrel, otherwise, the lens barrel is moved in a reverse direction. Meanwhile, Japanese Patent Laid-Open Publication No. 9-297336 teaches a camera in which a front end of the lens barrel is provided with a sensor for detecting a finger to prohibit a shutter releasing operation when the finger is sensed.
However, as for the cameras described in the above-noted publication Nos. 61-55099, 7-27150 and 7-218807, an operation for protection is performed after detecting a stoppage of the lens barrel so that it is impossible to prevent a strong load from being applied to the lens-barrel driving mechanism, although it is possible to prevent the strong load from being applied to the lens-barrel driving mechanism for the long duration. Incidentally, regarding the above-noted publication No. 9-297336, there is no description about a countermeasure in case the overlap of the finger occurs when the lens barrel is moved. Further, prevention against damaging the lens-barrel driving mechanism is not taken into consideration at all.
In view of the foregoing, it is a primary object of the present invention to provide a camera in which a lens barrier and a lens barrel are prevented from being damaged by overlap of a finger.
It is a second object of the present invention to provide a camera in which occurrence of mis-photographing may be reduced.
In order to achieve the above and other objects, the camera according to the present invention comprises a finger detection device for detecting a finger overlapping with a lens barrier or a lens barrel. The finger detection device includes a phase-difference detection circuit.
In a preferred embodiment, a number of the phase-difference detection circuits is two, one of which is used for the lens barrier and the other of which is used for the lens barrel. The respective phase-difference detection circuits are connected to detection electrodes to which capacitance is applied when the finger touches the lens barrier or the lens barrel.
Into the phase-difference detection circuit, two high-frequency pulse signals are inputted. One of the pulse signals is a detection-side pulse signal, and the other thereof is a reference-side pulse signal. In a normal state, a phase of the detection-side pulse signal is not delayed relative to a phase of the reference-side pulse signal.
However, when the finger touches the lens barrier or the lens barrel, the phase of the detection-side pulse signal is delayed owing to the capacitance applied to the detection electrode. Hence, the phase of the detection-side pulse signal is delayed relative to the phase of the reference-side pulse signal. Upon detecting the phase delay of the detection-side pulse signal, it is sensed that the finger overlaps with the lens barrier or the lens barrel.
In case the overlap of the finger is sensed while the lens barrier is moved or while the lens barrel is actuated, the lens barrier and the lens barrel are moved to a closed position and a collapsible-mount position respectively. Alternatively, the movement of the lens barrier and the lens barrel may be stopped. Besides these operations, a shutter releasing operation is prohibited and warning or the like is performed for a photographer.